1,081 research outputs found
Larval responses to turbulence and temperature in a tidal inlet: Habitat selection by dispersing gastropods?
No full textAuthor Posting. © Sears Foundation for Marine Research, 2010. This article is posted here by permission of Sears Foundation for Marine Research for personal use, not for redistribution. The definitive version was published in Journal of Marine Research 68 (2010): 153-188, doi:10.1357/002224010793079013.Marine larval dispersal is affected by hydrodynamic transport and larval behavior, but little is known about how behavior affects large-scale patterns of dispersal and recruitment. Intertidal habitats are characterized by strong and variable turbulence relative to shelf and pelagic waters, so larval responses to turbulence may affect both dispersal and habitat selection. This study combined observations and theoretical approaches to model gastropod larval responses to multiple physical variables in a well-mixed tidal inlet. Physical measurements and larvae were collected in July 2004 in Barnstable Harbor, Massachusetts (USA). Physical measurements were incorporated in an advection-diffusion model where larval vertical velocity is a function of turbulence dissipation rate, temperature, and the temperature gradient. Modeled larval distributions were fitted to observed concentration profiles by maximum likelihood to estimate larval behavioral velocity (swimming or sinking) as a function of environmental conditions. These quantitative behavior estimates were used to test hypotheses about behavioral differences among groups and to assess the relative impact of different cues on overall larval behavior. Larvae of five common gastropod species from different coastal habitats reacted most strongly to turbulence but had genus-specific responses to environmental cues. Larvae of a species from tidal inlets (the mud snail Nassarius obsoletus) had near-zero velocities under calmer conditions and sank in strong turbulence. In contrast, larvae from exposed beach habitats (Crepidula spp. and Anachis spp.) sank in weak turbulence and swam up in strong turbulence, with additional responses to temperature and temperature gradient. Larval responses also differed between small and large size classes and between flood and ebb tides. Behavior of mud snail larvae would contribute to retention inside the inlet and near adult habitats, whereas behavior of beach snail larvae would contribute to rapid export from muddy inlets lacking suitable adult habitats.This work was funded by the Woods Hole Oceanographic Institution (WHOI) Coastal Ocean
Institute, the WHOI Rinehart Coastal Research Center, the National Science Foundation (NSF OCE-
0326734), NSF and US Office of Naval Research grants to S. Elgar and B. Raubenheimer, and the
WHOI Sea Grant (National Oceanic and Atmospheric Administration, Grant No. NA16RG2273,
project no. R/O-38-PD). Analyses were completed while HLF was a postdoctoral scholar at Scripps
Institution of Oceanography (SIO), supported by the California Current Ecosystem Long-Term Ecological
Research program (NSF OCE-0417616) and by SIO funding to P. Franks
Climate change and drought in Minnesota and the Midwest
No full textThis document is intended to provide a brief overview of observed and projected changes to precipitation in Minnesota. Minnesota has become wetter on average over the past 120 years, and that trend is expected to continue, but climate change will likely make precipitation in Minnesota more unstable and intense. Between heavy rain events, Minnesota will likely have longer dry periods and more flash droughts. Transitions between very wet and very dry periods are also likely to accelerate.
Use this summary to learn more about the details of the projections and the potential impacts these changes could have on Minnesotans.Clark, Suzanna; Roop, Heidi A; Meyer, Nathan; Mosel, Jamie. (2023). Climate change and drought in Minnesota and the Midwest. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/257949
Mussel larval responses to turbulence are unaltered by larvalage or light condition
No full textLarval responses to hydromechanical cues potentially have important effects on larval dispersal and settlement. This study examined the behavior of mussel larvae (Mytilus edulis) in laboratory-generated turbulence representative of nearshore currents. We video recorded the behavior of early- and late-stage veligers in a grid-stirred tank at five turbulence levels under light and dark conditions. Water velocities and kinetic energy dissipation rates were measured using particle image velocimetry and acoustic Doppler velocimetry. We characterized the vertical velocity distributions for sinking, hovering, and swimming modes in still water and calculated the average larval behavioral velocity in turbulence. In still water, young larvae had more positive (upward) velocities than old larvae, and both stages had more positive velocities in light than in dark. In turbulence, the mean larval vertical velocity varied from positive at low dissipation rates to negative at dissipation rates above a threshold of 8.3 £ 1022 cm2 s23. At this threshold, the Kolmogorov length scale (h ¼ 590mm) was two to three times the mean larval shell lengths (171–256mm), implying that turbulence is detectable even by larvae that are smaller than the smallest eddies. Responses to turbulence were unaffected by larval age or light conditions and contributed substantial behavioral variation. By sinking in strong turbulence, mussel larvae could increase their flux to the bed in energetic coastal flows, particularly over rough substrates like mussel beds. The response to turbulence by early-stage larvae will also affect their dispersal and may help larvae remain near coastal populations.Peer reviewedOriginally published in Limnology and Oceanography: Fluids & Environments (2011) and available via this link: http://lofe.dukejournals.org/content/1/120.full.pdfCopyright 2011 by the Association for the Sciences of Limnology and Oceanography, Inc
Biophysical Constraints on Optimal Patch Lengths for Settlement of a Reef-Building Bivalve
No full textReef-building species form discrete patches atop soft sediments, and reef restoration often involves depositing solid material as a substrate for larval settlement and growth. There have been few theoretical efforts to optimize the physical characteristics of a restored reef patch to achieve high recruitment rates. The delivery of competent larvae to a reef patch is influenced by larval behavior and by physical habitat characteristics such as substrate roughness, patch length, current speed, and water depth. We used a spatial model, the ‘‘hitting-distance’’ model, to identify habitat characteristics that will jointly maximize both the settlement probability and the density of recruits on an oyster reef (Crassostrea virginica). Modeled larval behaviors were based on laboratory observations and included turbulence-induced diving, turbulenceinduced passive sinking, and neutral buoyancy. Profiles of currents and turbulence were based on velocity profiles measured in coastal Virginia over four different substrates: natural oyster reefs, mud, and deposited oyster and whelk shell. Settlement probabilities were higher on larger patches, whereas average settler densities were higher on smaller patches. Larvae settled most successfully and had the smallest optimal patch length when diving over rough substrates in shallow water. Water depth was the greatest source of variability, followed by larval behavior, substrate roughness, and tidal current speed. This result suggests that the best way to maximize settlement on restored reefs is to construct patches of optimal length for the water depth, whereas substrate type is less important than expected. Although physical patch characteristics are easy to measure, uncertainty about larval behavior remains an obstacle for predicting settlement patterns. The mechanistic approach presented here could be combined with a spatially explicit metapopulation model to optimize the arrangement of reef patches in an estuary or region for greater sustainability of restored habitats.Peer reviewe
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Heidi: Translated from the German of Johanna Spyri
No full textEarly edition of Heidi by Johanna Spyri, translated by H. A. Melcon. Except for a green and white boarder around the edge of the front cover, is a full page illustration of Heidi standing barefoot on a mountain clearing with her arms around two goats. On the ground around her feet are rocks, grass, and flowers. In the background are tall evergreen trees and mountain tops. The spine of the book is cream colored with the title and names of the author, series; Famous Books for Young Americans, and publishing company. Also on the spine is a small illustration of a girl in a long dress holding an umbrella with the word "illustrated" underneath it. On the inside of the cover is the flap of the dust jacket with text about the series. Behind the dust jacket flap is a bookplate for Gustine Courson Weaver. The paper attached to the interior cover and as part of the first page is a pale orange-peach color with a repeating pattern of squares with flowers in the shape of a C inside. The title page has a rectangle motif where inside has the title, name of the author, translator, and publishing company. On the center of the page is the logo for the publishers. On the opposite page is a full color illustration of Heidi and a girl named Clara sitting on stools on the ground outside while Heidi's grandfather offers them mugs of milk. Behind the girls are tall evergreen trees. In the background are the tips of mountains. The illustrated is captioned "Grandfather brought out two mugs of milk, one for Clara and the other for Heidi." On page 115 is another full color illustration. In the illustration are two girls, Clara and Heidi playing with kittens. Clara is sitting in a rolling wicker chair with a black kitten in her lap. Heidi is kneeling on the ground with a tan kitten on her shoulders and in front of her is a wicker basket with more kittens playing around and climbing out of. Behind the two is an older woman watching them in alarm. Behind them is a tall, multisided piece of furniture resting on a ledge. Behind the woman is a window with its curtains pulled to the side. The illustration is captioned, " Suddenly there jumped out of the basket one, two, three, and then some more kittens.
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Heidi
No full textEarly edition of Heidi by Johanna Spyri. The cover is made of a plain red cloth and on the spine is the title of the book, the face of a goat, and the names of the author and illustrator
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Heidi
No full textEarly edition of Heidi by Johanna Spyri. The cover of the book is red with white and black printed illustrations on it. The title and author's name are in gold. The illustration is over Heidi sitting across from a boy with her arm wrapped around a goat. In the background is a mountain with some trees and the sun peeking over the edge. On the inner cover is a illustrated print in bright green. In the illustration is Heidi standing in a forest with her arms held out above her head. On the cover page is a box which has some decorative motifs and contains the title and the names of the author, translator, author of the introduction, and the illustrator. Below that is a seal for the publishing company and then the locations and name of the publishing company. On the opposite page is an illustration of Heidi having a picnic with an older boy. They are sitting in a field holding bread and cheese. Behind them are several goats grazing on the mountainside. In the background is a forest of evergreens and more mountains
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Heidi
No full textEarly edition of Heidi by Johanna Spyri. Front cover is a yellow-aged white with green borders around the cover and illustration. The faded illustration on the cover shows two girls, one being Heidi, and a boy arm in arm walking through a grassy field. In the background are mountains and evergreen trees. On the title page is a light green printed illustration of two columns holding up a roof with vines and flowers. The title of the collection and book, and names of the author, illustrator, and publishing company are in black ink. In the middle of the page is an illustration of a castle on a cliff with a cloud in the background. On the opposite page is a full color illustration of Heidi sitting in a grassy field with a boy taking a nap. In her lap are purple blossoms. She is looking to the sky at a bird flying by. Behind her is a boy lying on his stomach with one of his arms pillowing his head as he takes a nap. In the background are mountains against a partly cloudy sky. The next colored illustration is of Heidi kneeling next to girl sitting in a plush chair, Clara, playing with two kittens. The final colored illustration included is of Heidi teaching a boy, Peter, how to read at a table. On the other end of the table is Heidi's grandfather smoking a pipe
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Heidi: From the German of Johanna Spyri
No full textEnglish translated version of Heidi. The front cover on the book is a light warm blue color with five white and green flowers, one white bud, and eight dark green leaves connected to each other by vines making a crisscross pattern of green and across the cover. All of the illustrations are line with gold. Wedged in between the two flowers at the top is a side profile of Heidi's face. On the center of the cover is the title and author in gold leafing. On the spine of the book are lines of dark green and gold at the top and bottom. Also at the top of the spine is the title of the book written in gold with a flourish underneath. Below the title is the last name of the author and a white flower lined in gold. At the bottom is a red and orange stripped stripe with "GCW" written in cursive above the name of the publishing company and stands for Gustine Courson Weaver. The interior of the book contains both black and white and colored illustrations of various scenes from the book. Some of the scenes are of Heidi with her grandfather, Heide, her grandfather, and Peter, and Heidi and Clara
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Heidi
No full textEarly edition of Heidi by Johanna Spyri. The title page has the name of the book, its author, and its illustrator spaced throughout the page and separated by illustrations of Heidi hugging a goat and another goat. Below that is the name of the publishing company and its headquarters location. On the opposite page is a banner with the title and author's name and illustration of a woman taking young Heidi up a mountain trail. Surrounding the trail is a field of grass. Beyond it are evergreen trees lining the edge of the partly cloudy sky. Below the illustration is some text reading "from the original title page". Several of the interior pages of the book have handwritten, cursive notes about the contents of the book
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